1. Field of the Invention
The invention concerns a method and a device for carrying out the method for automated recognition of semi-finished products, according to the pre-characterizing clause of claim 1.
2. Description of Related Art
For quality assurance, in a steel and rolling mill individual part tracking of semi-finished products, as part of process and plant monitoring, is indispensable.
During strand casting, all quality-relevant parameters of the casting process can be perfectly assigned to the individual strand section in the cutting station. So that the assignment of these parameters is retained even after the cutting station for every individual strand section, a marking which can be read by the human eye and/or by mechanical optical capture must be put onto the strand sections.
For this purpose, after the cutting station, a marking such as indented numbers, a bar code, a dot code, etc. is put onto the strand sections. Instead of being marked, the strand sections can also be made recoginsable by a sheet metal label with the appropiate data being hung, welded or nailed onto them.
In the prior art, the ability to track strand sections particularly in the case of mechanical reading of markings, is still subject to an error rate which is unsatisfactory in practice. Mechanical reading of an applied marking is understood to mean, on the one hand, geometrical recognition of the marking, and on the other hand the assignment of the semantic content of the geometrically recognised marking. If an error occurs in one of these steps, the mechanical identification of the strand section is unusable. Strand sections which cannot be identified mechanically must be identified by the human eye if possible, or remain unidentifiable and are rejected.
As well as a very wide variety of marking systems, a large number of devices to read the applied markings is known. All these systems are confronted, on the one hand, with the harsh operating environment of the steel mill, and on the other hand with the fact that in general the marking must be applied to the incandescent strand section. It must be possible to recognise markings mechanically and assign the casting parameters to the individual strand section in both the incandescent and the cooled state.
From JP-OS 2000-190257 A, a method of automatic recognition of strand sections after a cutting station of a continuous casting plant, particularly in a subsequent sorting point, is known. In a first step, numbers and/or letters are stamped into the strand section by a stamping machine. In a second step, the numbers and/or letters are recorded photographically by a camera in a first information picture. In a third step, there is a test for whether the semantic or read content of the stamped-in numbers and/or letters is recognisable. In a fourth step, the first information picture is stored together with the data which is specific to the strand section. In a subsequent sorting point, e.g. before the rolling process, a second information picture of the numbers and/or letters stamp is produced by a second camera, and the second information picture is compared with the first information picture by the comparison method and used for identification. This method makes it possible to identify badly readable or unreadable numbers and/or letters stamps, the semantic content of which cannot be completely determined, by means of the comparison method of the unreadable remaining numbers and/or letters. The device to carry out this method requires, as well as the stamping machine, two optical stamp reading machines, and in addition a database and a computer program for comparing the stamped-in numbers and/or letters in the first and second information pictures.